High tear strength resin-coated nylon fabric and method of making the same



United States PatentO HIGH TEAR STRENGTH RESIN-COATED NYLON FABRIC AND NIETHOD OF MAKING THE SAME Earle V. Painter, Newtonville, and Leonard D. Frisoli,

Boston, Mass., assignors to Fabric Research Laboratories, Inc., Boston, Mass., a corporation of Massachusetts No Drawing. Application August 20, 1949, Serial No. 111,572

6 Claims. (Cl. 117-76) The present invention relates to a waterproof cloth of superior durability and more particularly to a process for increasing the durability of rubber or synthetic rubber coated textile fabrics woven from yarns containing fibers of a synthetic high molecular weight polyamide and to the resulting products.

Waterproofed fabrics made by rubber coating a fabric woven from yarns containing synthetic high molecular weight polyamide fibers, hereinafter referred to as nylon and nylon fibers, came into experimental use during the recent war, and it was expected that such fabrics would prove to be highly desirable and effectivefor certain uses, because of the known high tensile strength of uncoated nylon fabric, and would permit the fabrication of tents, garments and other articles of remarkably light weight. However, in service such articles developed various defects leading to a short service life.

The present invention has as an object to provide a process for increasing the durability of such rubber coated nylon fabrics and to provide rubber coated nylon fabrics of enhanced durability. A further object is to provide a water-proof rubber coated nylon fabric of materially enhanced durability, as compared with the heretofore known coated nylon fabrics, without impairment of the flexibility or other desirable properties of such nylon coated fabrics.

Prior efforts to increase the durability of rubber coated fabrics have been directed primarily to modifications of the coating composition and to modifications of the re- 2,702,764 Patented Feb. 22, 1955 from synthetic or natural resins, etc., followed by coating of the fabric in the conventional ways with a rubber coating composition, results in markedly enhanced and superior tear resistance in the completed fabric and marked increase of the durability and service life of articles fabricated from the fabric.

The following examples of specific Ways in which our process may be carried out to produce our novel fabric are given by way of illustration and not of limitation of the invention.

Example 1 A light-weight fairly open weave nylon 2/1 twill weighing 1.6 oz. per square yard and woven from continuous filament yarns, Q. M. Corps Tentative Spec. P. Q. D. No. 358A was impregnated with of its weight of dioctyl phthalate on a laboratory Butterworth padder in which it was first immersed in the dioctyl phthalate and then squeezed in the nip of the padder rolls. The impregnated fabric was then knife-coated with 5.29 ounces per square yard of fabric of a polyvinyl chlorideacetate organosol containing 100 parts per 100 parts resin of dioctyl phthalate as a plasticizer. The fabric was heated in an oven to fuse the coating and convert it to solid dry condition. A control sample was made by directly coating, without pre-treating, a similar specimen of the same fabric. The Elmendorf tear energy (warpwise direction) was then determined for each sample from the average of three tests, from which it was seen that the tear strength of the coated fabric had been approximately doubled by the treatment of the example.

Example II The procedure of Example I was repeated, applying, however, a polyvinyl chloride-acetate organosol containing parts per 100 parts resin of dioctyl phthalate as a plasticizer, at a coating weight of 3.78 ounces per square yard of coating. The tear resistance of the fabric with this type and weight of coating was found to be more than doubled.

Further data on the procedures of Examples I and II anlg an analysis of these data are given in the following t8. $2

lationship of the coating to the fabric, e. g., the relative thickness of the coating, its degree of penetration into the fabric or into the yarns thereof, and by varying and adjusting the relationship between coatings on opposite sides of the fabric. While some improvement in durability can be obtained by a judicious selection and combination of such factors, the increase in durability heretofore so obtained has at best been no more than a small fraction of the original durability of the conventional coated cloth and of little practical significance. By our invention we provide rubber coated nylon fabrics having durability, as measured by tear strengths, as much as twice as great as those of comparable conventional coated fabrics.

An intensive study of the types and causes of failure of many salvaged military articles has shown that most failures of the article in service can be traced ultimately to an unexpectedly low tear resistance of the base fabric. Further investigation revealed, surprisingly, that coating of nylon fabric with an elastic flexible coating to waterproof it reduced the tear resistance of the base fabric to /a to /2 of its tear resistance before coating.

Our invention is based on our surprising discovery that impregnation of the base fabric, before coating, with a lubricant, for example, a plasticizer of the kind conventionally used in the formulation of plastic compositions The beneficial results of pre-impregnation of the nylon fabric with a lubricant appear to be substantially independent of the nature or amount of the coating subsequently applied to the fabric. While coatings of the vinyl chloride type have various advantages in association with a nylon fabric which has been given our pretreatment, and the organosol coating compositions are peculiarly advantageous because of the convenience and low cost of applying them to the pre-treated nylon fabric, our invention is not limited to this type of synthetic rubber or this form of resin composition and we may use instead coating compositions based on other polyvinyl resins, such as polyvinyl butyral or polyvinyl acetate, styrene and styrene derivatives, butadiene-styrene dispersions, butadiene acrylonitrile dispersions, natural latex, rubber solutions, etc., in any appropriate form such as solvent solutions, dispersions, or milled masses.

By the term lubricant as used herein we mean any material which lowers the coefiicient of friction between surfaces to which it is applied. We may use for this purpose, for example, mineral oil, paraffin wax, castor oil, sulfonated castor oil, or other natural or modified vegetable or mineral oils, fats or waxes. We also may use any of the organic, high boiling point compounds usually referred to in the plastics industry as plasticizers. Examples of plasticizers suitable for our purpose are: dioctyl phthalate, dibutyl phthalate, trioctyl phosphate, the sebacates such as dibutyl sebacate, and similar materials. 7

The amount of lubricant incorporated in the uncoated fabric in accordance with our invention is not critical and improvement in tear resistance is obtained with various amounts of lubricant. Desirably the amount should not be so great as to adversely affect the subsequentlyapplied coating or so great as to exude or bloom from the coated fabric.

We have found that the beneficial results of our process cannot be obtained merely by increasing the amount of plasticizer in the coating. Aside from the fact that the plasticizer content of the coating composition is in most applications fixed by the nature of the coating material and the use to which the fabric is to be put, omission of the plasticizer from the fabric and addition of an equivalent amount of plasticizer to the coating composition will not produce the increased tear resistance which is characteristic of our invention.

We claim:

1. A waterproofed cloth comprising a textile fabric woven from yarns containing fibers of a synthetic highmolecular-weight polyamide, a continuous impervious coating on the surface of said fabric bridging substantially all the interstices of the fabric, said coating being formed from a material selected from the group consisting of natural rubber and polyvinyl resins, and an impregnant in and on said fibers consisting essentially of a lubricant between the fibers and said coating, said lubricant serving to decrease the coefiicient of friction between fibers and between yarns and between the fabric and said coating, said lubricant facilitating relative movement between fibers and between yarns and between the fabric and said coating, said cloth having enhanced tear resistance as compared with a similar coated cloth the fibers, yarns and fabric of which are not so lubricated.

2. A waterproofed cloth comprising a textile fabric woven from. yarns containing fibers of a synthetic highmolecular-weight polyamide, an impregnant of dioctyl phthalate on and in said yarns and a coating on said cloth formed from a material selected from the group consisting of natural rubber and polyvinyl resins, said cloth having enhanced tear resistance as compared with a similar coated cloth the fibers, yarns and fabric of which do not contain a dioctyl phthalate impregnant.

3. The method of increasing the tear resistance of a coated cloth woven from yarns containing fibers of a synthetic high molecular weight polyamide which comprises impregnating a textile fabric woven from yarns containing fibers of a synthetic high molecular Weight polyamide with a lubricant which decreases the coefficient of friction between fibers, and thereafter providing the impregnated fabric with a continuous impervious coating bridging substantially all the. interstices of the fabric and formed from a material selected from the class consisting of natural rubber and polyvinyl resins, said lubricant facilitating relative. movement between fibers, between yarns, and between the fabric and said coating.

4. The method of increasing the tear resistance of a coated cloth woven from yarns containing fibers of a synthetic high molecular weight polyamide which comprises impregnating a textile fabric woven from yarns containing fibers of a synthetic high molecular weight polyamide with dioctyl phthalate and thereafter providing the impregnated fabric with a coating of a material selected from the class consisting of natural rubber and polyvinyl resins.

5. A waterproofed cloth comprising a textile fabric woven from yarns containing fibers of a synthetic highmolecular-weight polyamide, an impregnant of sulfonated castor oil on and in said yarns and a coating on said cloth formed from a material selected from the group consisting of natural rubber and polyvinyl. resins, said .cloth having enhanced tear resistance as compared with a similar coated. cloth the fibers, yarns and fabric of which do notcontain a sulfonated castor oil impregnant.

6. The method of increasing the tear resistance of a coated cloth woven from yarns containing fibers of a synthetic high-molecular-weight polyamide which comprises impregnating a textile fabric woven from yarns containing fibers of a synthetic high molecular weight polyamide. with sulfonated castor oil and thereafter providing the impregnated fabric with a coating of a material selected from the class consisting of natural rubber and polyvinyl resins. 7

References Cited in the file of this patent 

1. A WATERPROOFED CLOTH COMPRISING A TEXTILE FABRIC WOVEN FROM YARNS CONTAINING FIBERS OF A SYNTHETIC HIGHMOLECULAR-WEIGHT POLYAMIDE, A CONTINUOUS IMPERVIOUS COATING ON THE SURFACE OF SAID FABRIC BRIDGING SUBSTANTIALLY ALL THE INTERSTICES OF THE FABRIC, SAID COATING BEING FORMED FROM A MATERIAL SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER AND POLYVINYL RESINS, AND AN IMPREGNANT IN AND ON SAID FIBERS CONSISTING ESSENTIALLY OF A LUBRICANT BETWEEN THE FIBERS AND SAID COATING, SAID LUBRICANT SERVING TO DECREASE THE COEFFICIENT OF FRICTION BETWEEN FIBERS AND BETWEEN YARNS AND BETWEEN THE FABRIC AND SAID COATING, SAID LUBRICANT FACILITATING RELATIVE MOVEMENT BETWEEN FIBERS AND BETWEEN YARNS AND BETWEEN THE FABRIC AND SAID COATING, SAID CLOTH HAVING ENHANCED TEAR RESISTANCE AS COMPARED WITH A SIMILAR COATED CLOTH THE FIBERS, YARNS AND FABRIC OF WHICH ARE NOT SO LUBRICATED. 